1. Field of the Invention
The present invention relates to a structure for preventing a wrong insertion of a terminal into a terminal accommodating section in an electrical junction box or the like.
2. Description of the Prior Art
FIG. 10 is an exploded perspective view showing a conventional electrical junction box, wherein the junction box is composed of an upper casing 31 and a lower casing 32 respectively made of a synthetic resin material, together with a female coupling terminal 33 to be inserted into the upper casing 31 and a male terminal 34 to be inserted into the lower casing 32, and also a busbar 35 to be accommodated within the upper casing 31.
On the back surface of the upper casing 31, protrudedly provided are a terminal accommodating section 36 formed in a substantially rectangular tube shape for accommodating the coupling terminal 33 and a busbar receiving section 38 forming a groove 37 therein for receiving the busbar 35 and interconnecting the mutually adjacent terminal accommodating sections 36, 36. The coupling terminal 33 comprises an external peripheral wall 39 forming a substantially rectangular tube, which wall is further formed with a busbar receiving groove 40 for receiving the above busbar 35 and also a resilient contacting portion 41 (refer to FIG. 11) therein to be mated with the male terminal 34. The resilient contacting portion 41 is formed such that it is bent down inwardly near the upper end surface side of the wall 39, and further having a male tab contacting portion 42 to be contacted with the male terminal 34 and a busbar contacting portion 43 to be contacted with the busbar 35.
The busbar 35 is inserted and accommodated in the busbar receiving groove 37 of the upper casing 31, and enters inside the groove 40 of the coupling terminal 33 accommodated in the terminal accommodating section 36 so that it is connected with the busbar contacting portion 43. The male terminal 34 is inserted in a terminal receiving section 44 formed on the lower casing 32 with a male tab section 34a formed at the free end thereof protruded from the lower casing 32, which is to be brought into contact with the male tab contacting portion 42 of the coupling terminal 33, when the upper and lower casings 31, 32 are mutually fitted.
FIGS. 11 and 12 show a state in which the coupling terminal 33 is inserted in the terminal accommodating section 36. In the figures, it is shown that an overlapped portion 45 is formed at one side of the peripheral wall 39 of the coupling terminal 33 for the purpose of reinforcing the peripheral wall 39, and a relief groove 46 is formed in a notch-like shape for receiving the overlapped portion 45, whereby the orientation of the coupling terminal 33 is regulated only by inserting the overlapped portion 45 in the relief groove 46, and the coupling terminal 33 is prevented from coming off by inserting the busbar 35 into the grooves 37 and 40, respectively of the upper casing and the coupling terminal.
With the construction above, however, if a space gap between the coupling terminal 33 and the terminal accommodating section 36 happens to be made larger than the standard size because of the inconsistency of the manufactured dimensions thereof, the coupling terminal 33 can be accidentally accommodated in the terminal accommodating section 36, as shown in FIG. 13, even in a situation that the coupling terminal is rotated in the peripheral direction thereof as the overlapped portion 45 happens to be accommodated in the above inconsistent space gap, resulting that the busbar 35 and the male terminal 34 are improperly connected as a matter of fact.
In order to solve this problem, it can be arranged such that the peripheral wall 39 of the coupling terminal 33 is formed with a projecting portion 47, as indicated by a chain line in FIG. 13, and the accommodating section 36 of the upper casing 31 is formed with a fitting groove 48 for receiving the projecting portion 47. However, since such an additional member as the projected portion 47 has to be provided, an yield of the material prepared for manufacturing the coupling connector is deteriorated, and also a coupling terminal is often entangled with another adjacent terminal, thus making it difficult to handle them. Still further due to the fact that the fitting groove 48 is protrudedly formed, the space within the electrical junction box is also reduced as a whole, thereby deteriorating the distribution efficiency of the circuits or the like as well.